Adam Dachis

When packing a small bag for a trip, you can save a lot of space by treating your stuff like a bunch of matryoshka dolls. Simple nest smaller items inside of larger ones, and continue doing that until everything is packed. This way you'll actually pack your things instead of a bunch of air.

Redditor please_please_smee figured this out when packing shoes and socks:

When packing with limited space, stuff your shoes with two pairs of balled socks. Helps shoes maintain their shape and also saves space.

This tip works with many other items as well. Chargers fit in shoes, too. Rolling shirts inside of rolled up pants not only saves space but prevents wrinkles as well. It's easy enough to roll up cables and other little peripherals with your clothing as well. If something is moderately fragile, this can provide cushioning as well. Basically, when packing a bag you should consider what items you can combine and nest inside each other rather than simply putting everything side by side.